A lead-acid battery for starting an engine includes a plurality of electrode plate assemblies, a battery case, positive electrode straps, negative electrode straps, a positive electrode post, a negative electrode post, a cover, and an electrolyte solution. Each electrode plate assembly includes a plurality of positive electrodes, a plurality of negative electrodes, and a plurality of separators interposed therebetween. Each positive electrode strap is connected to the plurality of positive electrodes, and each negative electrode strap are connected to the plurality of negative electrodes. The battery case includes a plurality of cell compartments that receive insertion of the electrode plate assemblies. The positive electrode post is connected to the positive electrode strap in one of the cell compartments that is located at one end, and the negative electrode post is connected to the negative electrode strap in one of the cell compartments that is located at the other end. The cover seals the opening of the battery case, and includes a positive electrode bushing that receives insertion of the positive electrode post and a negative electrode bushing that receives insertion of the negative electrode post. The plurality of electrode plate assemblies are immersed in the electrolyte. A positive electrode terminal is formed by inserting the positive electrode post into the positive electrode bushing to form a unitary structure, and a negative electrode terminal is formed by inserting the negative electrode post into the negative electrode bushing to form a unitary structure.
A gap is provided between the outer circumferential surface of the negative electrode post (or positive electrode post) and the inner circumferential surface of the negative electrode bushing (or positive electrode bushing) in the negative electrode terminal (or positive electrode terminal) so as to enable smooth insertion of the negative electrode post (or positive electrode post) into the negative electrode bushing (or positive electrode bushing). If the gap is provided inattentively, the negative electrode terminal is easily corroded due to deposition of the electrolyte solution.
Patent Literature 1 discloses a configuration in which the gap between the outer surface of the negative electrode post (or positive electrode post) and the inner surface of the negative electrode bushing (or positive electrode bushing) in the negative electrode terminal (or positive electrode terminal) is limited to 1 mm or more. As a result of limiting the gap as described above, the electrolyte solution will not be easily deposited onto the gap, and corrosion can be prevented.